Effect of evolution for dispersed phase on thermoelectric performance of Yb0.2(CoSb2.875Te0.125)4

Abstract

CoSb3-based skutterudites, as a medium-temperature thermoelectric material, show excellent thermoelectric performance, but high thermal conductivity suppresses the high ZT value. Here, x% SnTe/Yb0.2(CoSb2.875Te0.125)4 samples were synthesized through vacuum melting reaction and spark plasma sintering (SPS). With increasing of SnTe content, the dispersed phase CoSb2, SnTe and CoTe2 appear successively via a selection of nucleation kinetics for 1%, 3% and 5% SnTe composited sample. Due to scattering of the dispersed phase and the solid solution distortion, lattice conductivity (κlat) of the 3% SnTe/Yb0.2(CoSb2.875Te0.125)4 sample decreases from 1.55 W m−1 K−1 to 1.19 W m−1 K−1 compared with the Yb0.2(CoSb2.875Te0.125)4 sample, which reduces by ∼22.8% at 773 K. The maximum thermoelectric merit ZT of the 3% SnTe/Yb0.2(CoSb2.875Te0.125)4 sample achieves 1.18 at 773 K.